One major obstacle facing health monitoring systems is the ability to accurately predict remaining life after structural state diagnosis. Today, many remaining life prediction models rely on empirical data which limits their applicability. Moreover, the large scatter in material data, i.e., fatigue, combined with archaic instrumentation has hindered the development and validation of improved prediction models. There is a need for long term continuous monitoring techniques capable of rendering a more precise and reliable stream of data that would enhance the modeling proficiencies and would ultimately help reduce maintenance cost, improve the longevity, and enhance the safety of civil infrastructures.Wireless sensors and sensor networks are emerging as sensing paradigms that the structural engineering field has begun to consider as substitutes for traditional tethered monitoring systems. A major consideration in using a dense sensor array for long term monitoring is the problem of providing power to the sensors. Piezoelectric energy powering has the added advantage to act both as the sensor and as the powering means, thereby reducing the power requirement and cost of the sensor system.Improving the piezoelectric power harvesting from civil structures' vibration while obeying environmental effects (temperature variation) is the first objective of this thesis; the application of a variable preloading condition is used as a solution to modify the cantilever piezoelectric harvester's properties. A generalized model that takes into account more than one vibration-mode shape is derived. Measured acceleration recordings from a concrete bridge deck under ambient loading and recordings from extreme events are used to show the gain in harvested energy when the harvester is in preloaded configuration. The effects of temperature variations on the piezoelectric (PZT) harvested energy from civil structures are also studied. A proposed mechanical tuning, based on the application of an axial load using Shape Memory Alloy to compensate the temperature effect, is presented.The work describing a fully deployed long-term piezoelectric based monitoring system with all needed attributes is the second objective of this work. The calibration and installation of the sensor is addressed. Defining the sensor output from real time loading distribution is shown. The evaluation of a full field data from a limited number of distributed sensor is studied. The damage prediction abilities of the long term self powered continuous monitoring system are evaluated. A slightly modified linear damage accumulation approach is then proposed using the damage index founded on continuum mechanics definition. The derivation of the damage index using sensor's output data is detailed with results from a set of laboratory tests, comparing the damage index prediction output from the sensor and values obtained using the complete time history data. Finally, a projection of the remaining life of tested specimens using reliability analysis was computed and it accuracy was evaluated by completing the test until failure and counting the total real observed cycles, showing very promising results for full field deployment and remaining life prediction with a reasonable accuracy.
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